A Jewish ritual bath, called a “mikvah” in Hebrew, is a small indoor pool. A mikvah often contains between approximately 1 to 15 metric tons of water, i.e., approximately 300 to approximately 4500 gallons of water. The water in a mikvah is used for religious purposes. For religious and sanitary reasons, the water is often replaced regularly. The water is heated to a comfortable temperature, but given that a mikvah often is a community-operated pool, heating the water must be often be accomplished with limited means and/or budgets. Heating the water to comfortable bathing temperatures may require capital investment, for example, purchasing, installing, and/or operating a heating system. Moreover, using electric heating systems and/or oil- or gas-burning heating systems can carry a high operating cost for electrical or oil consumption.
The need to heat other collections of water, for example hot tubs, Jacuzzis, swimming pools, whirlpools, bathtubs, and the like can also face challenges such as those mentioned above with respect to a mikvah. With respect to swimming pools, however, these concerns may be much more pronounced. In particular, swimming pools can hold an enormous amount of water. For example, some swimming pools hold millions of gallons of water and may be located outdoors. As such, heating the water in a swimming pool may entail enormous expense.